1. Planets Orbiting M Stars
Ian Crossfield
Sagan Fellow, UA/LPL
2015/11/02
Collaborators: K. Aller, T. Barman, C. Beichman, B. Benneke, J. Christiansen, D. Ciardi, S. Ciceri, J. Crepp, D. Dragomir, C. Dressing, BJ Fulton, T. Greene, B. Hansen, Th. Henning, A. Howard, H. Isaacson, H. Knutson, J. Krick, S. Lepine, M. Liu, J. Livingstone, L. Mancini, A. Martinez, T. Morton, C. Obermeier, E. Petigura, J. Schlieder, E. Sinukoff, M. Werner
K2's M Dwarf Systems
2015/11/01

2. Why Target M Dwarfs?
Increase the number of known M dwarf planetary systems;
Measure M dwarf planet frequencies vs. planetary and stellar properties;
Constrain models of planetary interiors and atmospheres;
Find planets in their stars’ habitable zones; and
Find targets for atmospheric studies with HST & JWST.
K2's M Dwarf Systems
2015/11/01

3. Planet frequency increases toward smaller and cooler planets: (for both M stars & FGKs)
RARE
Dressing+2013, 2015,
Howard+2012, Petigura+2013a,b
K2's M Dwarf Systems
2015/11/01
C MMON?

4. Half of all stars are less than ½ a solar mass
K2's M Dwarf Systems
2015/11/01

5. Small planets occur 2–3x more frequently around cooler stars:
Mulders+2014
See Gijs Mulders'
talk on Wednesday

6. But: only ~5% of confirmed transiting planets orbit M dwarfs!

7. K2's M dwarf advantage: Targeting more M dwarfs
Kepler
(slide from D. Huber)

8. K2's M dwarf advantage: M dwarf Habitable Systems
`Habitable Zone'

9. K2's M dwarf advantage: M dwarf Habitable Systems
`Habitable Zone'
K2's M dwarf “sweet spot”

10. M dwarf advantage: cooler stars & planets probe interior models at lower temperatures:
All planets w/ >4σ M & R:
(figure by E. Sinukoff)

11. M dwarf advantage: cooler stars & planets probe interior models at lower temperatures:
Cool planets w/ >4σ M & R:
(figure by E. Sinukoff)

12. Small M dwarfs are the best targets for transmission spectroscopy to probe exo-atmospheric makeup:λ1
Flux
Time λ2
C-H
stretch
CH4
CH4 Tp
µP ρp R*2
signal ~
C2H2 CO
Robinson+2014

13. Transiting Target Timeline
HST Operations
2015
2016
2017
2018
2019
2020
K2's M Dwarf Systems
2015/11/01

14. Transiting Target Timeline
HST Operations
2015
2016
2017
2018
2019
2020 }
Launch, check-out,
Cycle 1
K2's M Dwarf Systems
2015/11/01

15. Transiting Target Timeline
HST Operations
2015
2016
2017
2018
2019
2020 }
Calls for GTO, ESR, Cycle 1 Proposals }
Launch, check-out,
Cycle 1
K2's M Dwarf Systems
2015/11/01

16. Transiting Target Timeline
HST Operations
2015
2016
2017
2018
2019
2020 }
Calls for GTO, ESR, Cycle 1 Proposals
TESS operations }
Launch, check-out,
Cycle 1
K2's M Dwarf Systems
2015/11/01

17. Transiting Target Timeline{
HST Operations
2015
2016
2017
2018
2019
2020 K2 }
Calls for GTO, ESR, Cycle 1 Proposals
TESS operations }
Launch, check-out,
Cycle 1
K2's M Dwarf Systems
2015/11/01

18. So... what have we found?
K2's M Dwarf Systems
2015/11/01

19. Our team has found ~150 planet candidates in C0-C4
size ~ planet radius
K2's M Dwarf Systems
2015/11/01

20. M dwarf planet candidate population:
sensitivity
dropoff
See poster by
Arturo Martinez
K2's M Dwarf Systems
2015/11/01

21. Planet Size vs. Stellar Magnitude
FGK stars
M dwarfs
GJ1214
K2's M Dwarf Systems
2015/11/01

22. Adaptive Optics Followup
Imaging from:
Keck/NIRC2
LBT/LMIRCam
Gemini/NIRI
Hale/PHARO
RoboAO
We have followup imaging for ~all C0-4 planet candidates...
K2's M Dwarf Systems
2015/11/01

23. NIR spectra: IRTF/SpeX
~0.8—2.4 µm
(C. Dressing, J. Schlieder, K. Aller)
See Josh Schlieder's
talk on Wednesday
Schlieder et al., submitted
K2's M Dwarf Systems
2015/11/01

24. optical spectra: NTT/EFOSC
0.6—0.95 µm
(S. Ciceri,
C. Obermeier,
I. Crossfield)
Spectra in hand for ~all K2 M dwarf candidates
K2's M Dwarf Systems
2015/11/01

25. NIR spectra: NTT/SOFI R ~ 1000, ~0.9—2.4 µm A. Martinez, S. Ciceri,
C. Obermeier,
I. Crossfield
See poster by
Arturo Martinez
Spectra in hand for ~all K2 M dwarf candidates
Martinez et al., in prep.
K2's M Dwarf Systems
2015/11/01

26. Spectral Types of K2's M dwarf planet candidate systems:
Spectral types of candidates in C0-3:
K2's M Dwarf Systems
2015/11/01

27. Preliminary stellar parameters:
Stellar Radius
K2's M Dwarf Systems
2015/11/01

28. A few multi-planet M systems per K2 field
K2-3bcd
(Crossfield
et al. 15)
~1.9 RE
~2.3 RE
K2-5bc
(Montet
et al. 15)
~1.5 RE
~2.0 RE C3
multi...
See Evan Sinukoff's
talk on Wednesday
Several more in C4...
K2's M Dwarf Systems
2015/11/01

29. Photoeccentric Effect:
reveals several planets on eccentric orbits
P ~ few days
e > 0.2
M dwarf host
See Josh Schlieder's
talk on Wednesday
0.5
1.0
1.0
180
360
eccentricity
omega
K2's M Dwarf Systems
2015/11/01
omega

30. Habitability Index for Transiting Exoplanets
K2-3d
K2-3d
K2-18b
simulated
TESS yield
K2-18b
Barnes+2015
Montet+2015
Crossfield+2015
K2's M Dwarf Systems
2015/11/01
Habitability Index
Habitability Index
Stellar Insolation

31. Transiting Target Timeline{
2015
2016
2017
2018
2019
2020 K2 }
JWST Calls for GTO & Cycle 1 Proposals }
TESS operations
JWST Launch
K2's M Dwarf Systems
2015/11/01

32. JWST (and HST) targets are already here:
K2-3b: one µm transit spectrum would easily distinguish atmospheric makeup
Greene et al., submitted

33. JWST (and HST) targets are already here:
1.5 RE, ~300 K
2.2 RE, ~270 K
Being observed in HST GO &
Spitzer GO-12081
(PI: Benneke)
simulated data

34. K2 candiates require additional transits to refine timing:
Transit surveys measure
Uncertainty in transit time grows with time
K2's M Dwarf Systems
2015/11/01

35. K2 candiates require additional transits to refine timing:
Transit surveys measure
Uncertainty in transit time grows with time ? ?
(today)
(2019) ?
K2's M Dwarf Systems
2015/11/01

36. K2 candiates require additional transits to refine timing:
Transit surveys measure
Uncertainty in transit time grows with time ? ?
(today)
(2019) ?
For K2-3d:
σP = 8.5 min
In mid-2019: timing uncertainty is ±6 hr (1σ)
Pre-JWST transit followup is essential to maximize science return!
See Dan Bayliss'
talk on Wednesday
K2's M Dwarf Systems
2015/11/01

37. Spitzer transits are underway to ensure precise ephemerides in the JWST era:
(two transits of K2-3b)
Beichman et al., in prep.
K2's M Dwarf Systems
2015/11/01

38. RV spectroscopy already measuring masses for K2's M dwarf systems:
Cool planets w/ >4σ M & R:
K2-3b
(Alemenara et al. 2015)
(figure by E. Sinukoff)

39. Take-home Points:
K2 is finding lots of exciting M dwarf planet candidates!
(….. maybe fewer than expected?)
Validation & follow-up ongoing
O+IR spectra reveal stellar parameters
We're finding new planets that are
Temperate, Earth-sized;
Good RV targets (for masses)
Good HST/JWST targets (for atmospheres)
K2's M Dwarf Systems
2015/11/01

40. K2's M Dwarf Systems
2015/11/01

41. Looking for Hidden Giants:
Probable M giant
K2's M Dwarf Systems
2015/11/01

42. K2 M Dwarf Advantage: Numbers
Kepler sample (Dressing et al. 2015):
2543 stars (all observed for ≥ days)
Most have T eff ≥ 3500 K, R ≥ 0.4 R sun
157 planet candidates
K2:
Observing ~ M dwarfs per field
≥ 10 fields, ~ 80 days each
The K2 M dwarf advantage:
5000*80*10 / 2543*1000*1 ~ 1.5x

43. TESS K2 Kepler Temporal coverage Sky coverage K2 sky coverage K2
Kepler
Temporal coverage
K2's M Dwarf Systems
2015/11/01
Sky coverage

44. Expected yields: K2 and TESS
K2 yield to date (4 of 14 fields)

45. Expected yields: K2 and TESS
K2 yield to date (4 of 14 fields)
TESS yield:
Ashley Wilkins;
Sullivan+2015